Control circuit for radio transmitters



Jan. 1, 1935. A. GEBHARD CONTROL CIRCUIT FOR RADIO TRANSMITTER S Filed Dec 5, 1928 2 Sheets-Sheet 1 INVENTOR. at www, ugwywei,

ATTORNEYS.

Jan. 1, 1935. A. GEBHARD ,7

CONTROL CIRCUIT FOR RADIO TRANSMITTERS Filed Dec. 5, 1928 2 Sheets-Sheet 2 m INVENTOR. e uawgw, Lg I I ATTOURIGEY.

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1' t it ,986,722 r i ONTROL cmcorr FOR, RADIO 1 Y M a TRANSMITTERSH ,v v U juiSiALGebhard; Washington, 11.0 assi'gmmy t v v q. mesne'assignments; to Wired Radio, Inc., New i ork; NrYgacorporation er Delawar in r l invention relates .to transmitting systems in :general; and more" specifically to :control circuitsof radiotransmitters; r 1

1 the length of timethatthe control keymay be An object of, myinvention isJ-toprovidegcertain improvements in; radio transmitterswhereby an overload condition caused by impropercontrol circuits prevents damage to. the transmitting ap- Another object my invention is to' provide a contr-olicircuit, for i a; radio transmitter whereby depressed isautomatically controlled;

Afurther object of my invention istoy provide a control circuit adapted to, open the keying circuit of a radio transmitter when the key circuit hasbeemclosedifoi anpredetermined length of time and'to completely remove'all potential from the. transmitting tubes, when the key circuit con- ,tinues closed for an additional length oitime; 1 i: Other and iurther obiecjtso myfl en n side in the circuit arrangement a better under-p standing of which can be ;had iromthe ,specifica:

tion; following i and ;by referring to ,the; accorn panying drawings wherein Figs; 1 and 2 are diagrams. showing'the control circuit for radio trans: mitters of myinvention. 1Q. i

, In radio transmitting systems employing; there mionic ,tubes it 1is; necessary to employ a source or several sources. of electrical energy for ,ener-agizingthe;respectiyeelectrodesoithe tubes. In

most installations; it is the common practiceto employ relays or contactors incircuit with the source oft energy and the tubes as a means for starting and stoppingthe set.

and a common source of electrical energy; and the energization of one depending upon the pre:-

Y energization of another. Included inthe cornsources 5, 9 and 11.

energy a momentary contact switchmaybe emin, thermionic tubes 1, 2 and 3, each having a plurality of electrodes which are energized by The cathodes of thermionic tubes 1, 2 and 3 are energized from source 5 by means of transformer 4. Relay 6 is provided IWlth suitable contacting members, which when closed complete the energizing circuitto the primary circuit of transformer 4. The: anodes of thermionic tubes 1,2 and 3 are energizedfrom source 91 by means of contacting members asso- The relays or contactors; may-be controlled by a common circuit pre-energization of relayl8. The energization of relay S-is dependentuponthe closing of momen-h tary contact switch memberfl. Source of potena tial 11-1is provided for energizing thelrespective I control electrodes of therrnionic tubes.1,"2and'3.

i In transmitting systems" for the, transmission of code some method must be employedfor starting and stoppingoscillations or an equivalent result the starting andstopping .oi the amplifier tubes. It is well recognized by those skilled in the art that a satisfactory-method of keying employs a source of negative control electrode bias supplied totubes, which bias is lowered in value when transmission of a 'code character is desired. Such a methodof keying is. illustrated in the ac companying drawings. 3 In the schematic circuit arrangement shown-inFig. 1 of the accompanying drawings, the controlelectrode of thermionic tube 2 iscontrolled byfthismethod. The control electrode of thermionic tube 2 is normally supplied with energy from source 11 by means of resistor 12b and the, return circuit including C the cathode; The potential supplied the control electrode may be of a. negative polarity in-respect.

to the polarity of thecathode. 1 The value of potential. with. a given source would be governed by the value of resistor 12b. A resistor 120 is connected in parallel withysourcell and acon nection madethereon near the cathode potential end. This connection leads to the contacting:

member associatedwith armature 12a of electromagnet 12. A contact member positioned adjacent to armature 12a, provides a complete circuit from" theicontrol electrode of thermionic-tube 2 'toresistor-l2c." The value oi negative potential supplied the control electrode of thermionic tube 2 may be of a much lower value when the supply vof energy isfrom source 11 by means of the contacting members; This change in the potential supplied the control electrode of thermionic tube 2 causes the operating characteristics of the tube to be proper for eflicient amplification of the energy from thermionic tube 1. Electromagnet 12 is energized from source of energy 13. The closing of key 14 completes the energization of electromagnet 12 and the actuation of armature 12a.

The-solenoid of a retardard relay is connected to source of enregy 13 and key 14. Solenoid 15 is energized by means of closing key 14 thereby completing the circuit to source of energy'13. Solenoid 15 is electromagnetically associated with an armature 16. Armature 16 is-provided with a suitable retarding device 16a which may com- .ciated with the armatureof relay 10. The energization of relays 6 and 10 is dependent uponthe' prise a dash-pot as show or any suitable bellows arrangement." An insulated arm 17 is positioned to armature 16 and is provided with suitable contacting members 18 and 13a. Contacting members 18 normally complete the key circuit from v source 13 through key 14 to electromagnet 12.

Contacting members 180, are normally closed thereby allowing the energization of relays 6, 8 and IQ by the closing of .momentary contact switching member '7. The opening of contacting members 18 and the opening of contacting members 18a is retarded by dash-pot 16a. 1

The opening of contact members 18 precedes the opening of contact members l8a:...-.1 ig ;2iof the accompanying drawings shows individual retarded armatures 16 and l6alwithwhich areas:

sociated individual contact-members 18 and 18a;

Each of the armatures have different retardation" properties.

ranged to shortcircuit an'electromagnet and thus Fig. 1 of the accompanying-drawingsshows contact members 18 and 18a associatedwith a;

common armature 16. In the ordinary course of keying the :Jenergization v,0fl electromagnet 12. is; completed. If,however;xkey 14 is depressed for.

1 apredetermined lengthof. time, armature. 16 will .overcomelthe retardation efiect of dash-pot 16a;

and contact. members 18 will 'open the circuit thereby causingno energization of electromagnet vl2with the depression :of key .14. If key 14 is possible "without departing from the spirit of my invention. Contactmembers may be provided on a suitable retarded armature whereby the circuit is completed when the armature is actu-' ated. The completion of the-circuit can-be ar-' deenergize thev set. I A I It'is to be understood that many modifications of the control circuit for radio transmitters :of my invention other than as shown'in. the representative circuit arrangement illustrated in theaccompanying I drawings are possible without, de-

parting from the spirit of my inventionand it is not intended to restrict the embodiments of my invention tothe gforegoing specification or the accompanying drawings but only as defined in the accompanying claims.

What I claim as new and desire to secure by Letters Patent of the United States is as follows:

1. In an electron tube system, an electron tube' having a plurality of electrodes, a conditioned circuit, controlling ,means ,fr--S11Pplyinga predetermined potential to one oisaidlelectrodes, other energy controlling means for supplying energy to other of said electrodes, and control means respbnsive to certain predetermined conditions in 'said conditioned circuit for controlling said first mentioned control means and responsive to furthen and subsequent. predetermined conditions of said oonditio n cir cuit for effecting the control of said ;other. .controlrmeans.

2. The combination in accordance with claim *1 inwhich-saidconditioned circuit includes signal modulation means and in which said predetermined conditions correspond to predetermined conditionsin saidisignalling circuits 3; The combination in accordance-with-claim l in which said first mentioned electrode comprises the control electrode and said first :mentioned energy:controlling means supplies biasing potential thereto;- a

4; .The combination inaccordance with claiml in which said other of said electrodes includesat leasta cathode and an anode and in which said seconddmentioned control means controls the energization of said electrodes.

5. The combination in accordance-with claim-1 in. which said first mentioned: electrode and-said first mentioned control means comprises-biasing energization means, and inwhich said other ofsaidilelectrodes includes-atleast a cathode andanode and in which said-second :mentioned control means comprises 'energization :means for said electrodes. I v i I 6. The cornbination in accordance with claim 1 in which said conditioned circuit includes-a key andtime controlled relayresponsive to different predetermined-durationsenclosure of said key.

7. The combination-inaccordance with claim 1 in which said conditioned-circuit includes a key and time controlled relay means responsiveto difierent durations of closure of said key; said first mentioned electrode comprises a control electrode, said first mentioned controlling means com-- prises biasing energizatio-n-means for said electrode, said other-electrodesinclude -at--least-a cathode and ananode; andsaid'secondmentioned control means incl-udesencrgization means for said-electrodes.-- I

. H 1 LOUIS A. GEBH-ARD; 

